I remember that their mother(she was blonde) told them to become bank robbers. Many of them get killed after a last bank robbery because it took them a long time! At the end, Mother and her last son were surrounded by the local police and bruttaly killed with lots of bullets..
Please help me! Thank you very much!

Marija, there have been a number of movies made that were loosely based on Ma Barker and her bank robbing sons. Since you haven't provided dates, it is hard to pin down which one you are talking about so I am going to give you a few links to review.

Here is some history on them:
Ma Barker - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Ma_Barker)

Within that link, they mention the following movies. One of them might be the one you are looking for:

Public Enemies (Video 1996) - IMDb (http://www.imdb.com/title/tt0114202/)

Bloody Mama (1970) - IMDb (http://www.imdb.com/title/tt0065481/)

Ma Barker's Killer Brood (1960) - IMDb (http://www.imdb.com/title/tt0054041/)